Dual passage well drilling pipe



' Nov. 27, 1962 N. c. WELLS 3,065,807

DUAL PASSAGE WELL DRILLING PIPE Filed June so, 1958 2 SheetS- -Sheet 1 MG! E 2.

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: M 14 T' 10 J J26 A r 1 -2a 24 $25 I I 50 r26 INVENTOR. v 27 Mew/2W (I M245 4 B N. C. WELLS DUAL PASSAGE WELL DRILLING PIPE Nov. 27, 1962 2 Sheets-Sheet 2 Filed June 30, 1958 INVENTOR.

Arr0PMV United States Patent Oflice 3,065,807 DUAL PASSAGE WELL DRILLING PIPE Norman C. Wells, Long Beach, Calif, assignor to Gas Drilling Services Co., Los Angeles, Calif, a partnership Filed June 30, 1958, Ser. No. 745,743 4 Claims. (31. 175-321) This invention relates to improvements in well drilling pipe rendered particularly adaptable to drilling with circulated gas, as distinguished from liquid or mud, by making up the drill string with stands of concentrically spaced pipes forming continuous, separate circulation passages. In certain of its aspects the present invention has to do with improvements in drilling string structures dealt with in the Grable application Serial Number 380,983, now Patent No. 2,850,264, filed September 18, 1953, on Dual Passage Drill Strings.

Generally contemplated are new features of particular structural and operational advantage for incorporation in dual pipe drilling string in which I may use for the outer pipe, standard drill pipe with little if any modification, which has the advantage of such features as general availability, maximum strength consistent with internal diameter desirabilities for the present invention, and conformability to common practices in handling and assembling in all drilling operations.

My major overall object is to improve the structural and functional association of the inner pipe with the outer string, in a manner permitting of most practical and economical construction and interconnection of the inner stands, and their association with the outer stands in a relation afiording greatest facility in assembly and replacement of the inner pipes within their respective outer stands. Generally considered, the invention contemplates associating or interconnecting the inner stand ends with telescopic joints, the range of which will permit full shouldered make-up of the outer stands and also allow for all such relative expansion of the inner and outer pipes as may occur, while maintaining fluid seals in the telescopic joints.

An important particular object is to removably accommodate the inner stands in the stated relation, so as to permit their replacement in the outer stands when they may become worn, or require inspection or repair. This same feature of removability favors the practicability of making the inner stands of less expensive pipe or tubing and in an economical manner with ordinary shop facilities or even at the well itself. Further, the inner stand structure and mounting render more feasible the use of lighter weight or thinner wall tubing, and the choice of a Wider range of materials, metallic and non-metallic, for their formation.

As to the inner stand mountings, the invention contemplates vertically supporting each inner stand within its respective outer stand, while maintaining the pipes concentrically spaced at substantially corresponding inner and outer passage areas. In supporting the inner stand, the latter is provided with external projections removably engaged against the outer stand, and preferably in a manner such that despite the disengageability of the stands, the inner is both supported and rotationally driven by the outer stand.

Most desirably, I provide the inner stand at or below its enlarged telescopic joint end, with projections received within the surrounding outer pipe tool joint, as by receiving the projections in a space or spaces, be tween the pin end and interior shoulder formation within the box section below its threads. As will appear, the inner stand may readily be run in the outer stand to seat within the tool joint box and in a relation making it possible to lower and connect a similar dual pipe stand was: Patented Nov. 27, 1962 above, with the same facility with which standard drill pipe may be made up.

The invention also contemplates the use of an additional, or alternative form of releasable connection between the inner and outer stands, by providing on the former, flexible wire-like projections which resiliently engage the outer pipe to a degree which can cause the outer pipe rotation during drilling to be transmitted to the inner pipe at locations that may be spaced, as desired, along the latter.

All of the features and objects of the invention, as well as the details of certain typical and illustrative embodiments, will be understood more fully from the following description of the accompanying drawing, in which:

FIG. 1 is a view showing a dual pipe drill string made up in accordance with one embodiment of the invention;

FIG. 2 is an enlarged fragmentary view of the FIG. 1 structure taken at one of the outer string tool joints;

FIGS. 3 and 4 are cross sections taken respectively on lines 3-3 and 4-4 of FIG. 2;

FIG. 5 is a view similar to FIG. 2 showing a variational form of the invention;

FIG. 6 is a cross section on line 66 of FIG. 5; and

FIG. 7 is a fragmentary sectional View illustrating a further modification of the invention.

Referring first to FIG. 1, the dual pipe string, generally indicated at 10 is shown to be made-up and employed for the purpose of drill pipe employing gas circulation, run down in a well defined by the upper cased section 11 and the open hole 12 below. Generally considered, the composite drill string 10 comprises an outer pipe string 13 which may be made-up of standard drill pipe externally upset at 14 and 15 to form the standard threaded pin and box tool joints 16, and an inner pipe string 17 composed of stands 18 of pipe or tubing interconnected at 19 by telescopic joints Within the tool joints 16. The outer and inner pipe stands are concentrically spaced to form an outer annular passage 20, the minimum cross sectional area of which along its extent, corresponds substantially to the cross sectional area of the inner passage 21 within the stands 18. The lower end of the outer string 13 is shown to have a standard tool joint connection at 22 with a sub or shank 23 to which is welded or otherwise attached a drill bit which may be of any suitable design and construction adapted to receive circulating gas discharged downwardly through passage 24 which is a continuation of passage 20, and to return the gas together with entrained cuttings upwardly through pipe 25 concentrically spaced within the sub 23 by welded lugs 126, for return flow through passage 21 to the ground surface. Merely as illustrative, the bit 26 is shown to contain outer passages 27 receiving the gas from passage 24 and communicating with passages 28 within the outer cutting edge or edges 29 of the bit, with a central passage 30 in open communication through pipe 25 with passage 21. As will be understood, the gas in flowing through passages 27 and 28 sweeps inwardly and entrains the bit cuttings as they are formed, so that the latter are carried upwardly, through the inner string for separation of the cuttings from the gas at the ground surface, pernitting recirculation of the gas downwadly through the outer passage 20.

Referring to FIG. 2, the externally upset tool joint 16 is shown to comprise the usual taper-threaded box 33 having below the threads, an annular shoulder 34, and a correspondingly threaded pin section 35 having above its threads a shoulder 36 which engages against the upper end face 37 of the box section in the fully made-up condition of the joint.

The telescopic joint structure 19 terminally interconnecting the inner pipe stands 18 is shown to comprise a sleeve 38 welded to the upper end portion of a lower stand and projecting therefrom to receive the lower end of the stand next above. Preferably, the latter has at 39 a substantially straight sliding fit within the sleeve 38 and the ends of the pipes are spaced at 49 so that the inner stands are free for longitudinal expansion and contraction in the fully made-up condition of the tool tool joint 16. Fluid leakage and consequent erosion or wear through the telescopic joint is prevented by one or more seals 41 consisting preferably of O-rings 42 seated in annular recesses 43 within the wall of the sleeve 38. Being so located, the rings are accessible for inspection or replacement through the open end of the sleeve when the pipe above is removed. It is to be particularly noted that the sleeve 38 terminates below the upper end of the tool joint box 33, and the lower end of each pipe 18 terminates above the lower end of the pin 35 opposite. Thus, while being accommodated for direct telescopic making within the tool joints, the ends of the inner pipe and sleeves 38 are protected against possible damage in making up or disconnecting the stands, as might otherwise occur if the inner parts were exposed beyond the tool joint ends.

Provision is made for centralizing and vertically supporting the inner stands 18 in a manner allowing full freedom for expansion and contraction relative to the tool joints and outer stands, and permitting easy removal of the inner stands for inspection, replacement or repair. I also adapt the inner stand supporting means to forms and constructions which facilitate making of the complete inner pipe sections to the extent that they can be fabricated, reconstructed or repaired without special facilities and in any machine shop or even at the rig itself. This objective is achieved generally by employing removable or easily disconnectible supporting means allowing amply free gas circulation through the passage 20, and by allowing for telescopic and sealed accommodation of the inner pipe within the sleeve 38 to a degree that does not require exactness in the overall length of the pipe.

According to the form of the invention shown in FIGS. 2 to 4, the pipe 18 carries directly below the sleeve 33 a plurality of circularly spaced welded-on lugs 44 which seat on the tool joint box shoulder 34 to vertically suspend the pipe. The lugs are disengageable from the seat to permit removal of the inner pipe upon disconnection of the tool joint parts. When assembled as in FIG. 2, consequential upward displacement of the inner pipe is prevented or limited by engagement of the lugs 44 wtih the lower end 45 of the pin 35.

Support may also be given the inner pipe, if desired, by means in addition to the lugs 44, and particularly for the purpose of affording additional centralizing and transmission to the inner pipe of the outer string rotation as during drilling. Such additional supporting means may comprise assemblies 46 of circularly spaced, resilient wire-like fingers carried by the inner pipe 18 more or less proximate to the lugs 44 and at one or more intermediate locations. Referring to FIG. 4, each spring finger assembly 46 is shown to comprise a ring 47 welded or otherwise fixed to the pipe 18 and carrying generally tangentially projecting wires 48 of Phosphor bronze or other non-sparking metal, extending from coils 49 of the wires at their juncture with the ring 47. As will be apparent, the fingers 48 project in a direction such that clockwise rotation of the outer string 10 will produce corresponding rotation of the inner string 18. While affording some vertical support for the inner pipe and the described rotation transmitting association of the outer and inner strings, the assemblies 45 may be readily withdrawn from the outer stands as the inner pipe is pulled therefrom.

FIG. illustrates a variational form of the invention in which lugs 50 which otherwise correspond generally 4- in structure and function to the previously described lugs 44, are used to serve the dual functions of vertically suspending the inner pipe 18 and transmitting thereto the rotation of the outer string, and to the exclusion of the spring finger assemblies 46 if one or more of the latter may not be desired. Here the lugs 50 are shown to be received downwardly within radial notches or recesses 51 in the wall of the tool joint box 33 below the shoulder 3411. Thus the inner pipe 18 is vertically supported by the resting of lugs 50 on the inclined shoulders 52 at the bases of the recesses 51, and the outer string rotation is transmitted to the inner string by the confinement of the lugs between the sides 53 of the recesses, see FIG. 6.

FIG. 7 illustrates a further variation of the invention different from the previously described forms, primarily with respect to the association of the pipe supporting lugs with the tool joint box. Here the lugs 54 are shown to be set upwardly within notches 55 in the bottom of the sleeve 38, and to be externally threaded at 56 so that the lugs will screw into the lowermost of the box thread to the point of engagement with the bottom inclined surfaces of the lugs with the box shoulder 34. Unscrewing of the lugs may be prevented by light spot welding of one or more of the lugs at 54 to the tool joint, the weld however being sufficiently light or small as to be readily ruptured by an appropriate tool applied to the lugs when it is desired to remove the inner stand. The latter may rely for its concentric spacing from the outer stand, solely on the lugs 54 and the telescopic joint 19 below, or the pipe 18 may carry welded-on lugs 53 at one or more locations along its extent, the lugs being slidable along the wall of the outer stand and therefore being removable when the inner pipe is pulled therefrom. The presence of a light spot weld as at 57 does not alter the essential removability of the inner stand because of the aforementioned weakness and ready rupturability of the weld. In fact it may not be necessary to apply the weld to the lug itself, but merely use the weld spot applied to shoulder 34, as a stop to arrest or limit unscrewing rotation of the lugs.

Pertinent to the desirability for maintaining substantially equal minimum cross-sectional flow areas within the passages 20 and 21, the following typical dimensions may be given. Using drill pipe It) having an internal diameter of 3% inches, the inner pipe 18 may be formed of tubing having 2 /2 inch OD. and 2%; I.D., the sleeve 38 having an CD. of 3 /8 inches. Thus, pipes 18 have cross-sectional areas of about 3.55 square inches, with cross-sectional areas in passage 20 below the sleeves 38 of about 6.10 square inches and approximately 3.32 square inches between sleeve 38 and the bore wall of the pin 35.

By reason of the easy removability of the inner stands 18 and the simplicity of their construction and the combination within the outer stands, the invention renders fully practical the use of materials for the stands 18 which may be specially selected for any of various particular purposes such as lightness in weight, special corrosion or erosion resistance, and minimum Wall thicknesses consistent with such requirements, thus the inner stands may be made of ferrous or non-ferrous metals, or even such non-metallic materials as may be adequately durable and resistant to all the wear factors encountered in drilling.

Normally the inner pipe stands will be removed from their respective outer stands in the course of pulling the entire string from the well. Circumstances may arise necessitating removal of the inner stands while the outer pipe remains in the well. For this purpose it is contemplated that the lugs 44, 50 or 54 may be made of aluminum alloy or other metal having known solubility in caustic solution, which may be put down into the outer passage between the stands to dissolve away the lugs to the extent that the inner stands may be pulled from the well.

I claim:

1. A drilling string for gas circulation comprising upper and lower stands of outer drill pipe interconnected by a tool joint including a threaded box section formed by an externally upset integral end of the lower stand and a threaded pin section integral with an externally upset lower end of the upper stand and screwed into the box section, shoulders on said sections interengaging to positively limit the screwed-in position of the pin section, upper and lower stands of inner pipe contained respectively within said upper and lower stands of the outer pipe and concentrically spaced therefrom to form continuously open inner and outer passages, an inner joint interconnecting the ends of said inner stands within said tool joint, means providing vertical support of the inner string by the outer string and interconnecting the inner and outer stands for simultaneous rotation together, and flexible wire-like fingers carried by said inner stands and frictionally engaging the walls of said outer stands.

2. A drilling string for gas circulation comprising upper and lower stands of outer drill pipe interconnected by a tool joint including a threaded box section on the upper end of the lower stand and a threaded pin section on the lower end of the upper stand and screwed into the box section, upper and lower stands of inner pipe being of smaller outside diameter than the inner diameter of the outer drill pipe and contained respectively within said upper and lower stands of the outer pipe and concentrically spaced therefrom, the inner pipe defining a continuously open inner passage and the space between the inner and outer pipes defining a continuously open outer passage, an inner joint interconnecting the ends of said inner stands within said tool joint and formed by an outer enlarged end of one inner stand receiving the end of the next stand in straight sliding telescopic relation, and means including circularly spaced external projections on said inner stands, said means including means of wire-like form frictioually engaging and bearing against the inside of the outer stands to vertically support the inner stands thereby and to transmit rotation of the outer stands to the inner stands, said projections being releasable from their engagement with the outer stands so that the inner stands are withdrawable therefrom when the outer stands are disconnected.

3. A drilling string for gas circulation comprising upper and lower stands of outer drill pipe interconnected by a tool joint including a threaded box section on the upper end of the lower stand and a threaded pin section on the lower end of the upper stand and screwed into the box section, upper and lower stands of inner pipe being of smaller outside diameter than the inner diameter of the outer drill pipe and contained respectively within said upper and lower stands of the outer pipe and concentrically spaced therefrom, the inner pipe defining a continuously open inner passage and the space between the inner and outer pipes defining a continuously open outer passage, an inner joint interconnecting the ends of said inner stands within said tool joint and formed by an outer enlarged end of one inner stand reeciving the end of the next stand in straight sliding telescopic relation, and means including circularly spaced external projections on said inner stands bearing against the outer stands to vertically support the inner stands thereby and to transmit rotation of the outer stands to the inner stands, said projections being relesable from their engagement with the outer stands so that the inner stands are withdrawable therefrom when the outer stands are disconnected, said enlarged end of said one inner stand being formed by an attached sleeve and the last mentioned means including means of wire-like flexible form carried by the inner stand below the sleeve and frictionally engaging the outer stand.

4. A drilling string for gas circulation comprising upper and lower stands of outer drill pipe interconnected by a tool joint including a threaded box section on the upper end of the lower stand and a threaded pin section on the lower end of the upper stand and screwed into the box section, upper and lower stands of inner pipe being of smaller outside diameter than the inner diameter of the outer drill pipe and contained respectively Within said upper and lower stands of the outer pipe and concentrically spaced therefrom, the inner pipe defining a continuously open inner passage and the space between the inner and outer pipes defining a continuously open outer passage, an inner joint interconnecting the ends of said inner stands within said tool joint and formed by an outer enlarged end of one inner stand receiving the end of the next stand in straight sliding telescopic relation, and means including circularly spaced external projections and flexible wirelike projections on said inner stands bearing against the outer stands and frictionally engaging the walls of said outer stands to vertically support the inner stands thereby and to transmit rotation of the outer stands to the inner stands, said projections being releasable from their engagement with the outer stands so that the inner stands are withdrawable therefrom when the outer stands are disconnected.

References Cited in the file of this patent UNITED STATES PATENTS 474,080 Bullock et a1 May 3, 1892 1,732,791 Crowell Oct. 22, 1929 1,781,049 Brinton Nov. 11, 1930 1,839,844 Granger Jan. 5, 1932 1,868,400 Stover July 19, 1932 1,981,863 Harris Nov. 27, 1934 2,075,130 Osterholm Mar. 20, 1937 2,100,420 Wright NOV. 30, 1937 2,483,591 Nichols Oct. 4, 1949 2,701,122 Grable Feb. 1, 1955 2,735,495 Hall Feb. 21, 1956 2,850,264 Grable Sept. 2, 1958 

